The present invention relates to a blow-out protector and fire control system for petroleum exploration.
Blow-out protectors are well known. In general, they are valve devices which are designed to pack off the annular space between the drill pipe and the well casing, or a blow-out protector housing which forms an extension of the casing, in the event of a blow-out. A typical blow-out protector comprises, as its essential components, an elastomeric body which performs as a packing component and an exteriorly operated actuator means which acts on the packing element and forces it into sealing arrangement between the drill pipe and the casing or housing. Usually, the blow-out protector includes or is associated with some means of sensing or reacting to an increase of pressure in the well hole and is designed such that the protector is actuated and the well pressure is controlled before the well pressure can do substantial damage to the drilling equipment or cause injury at the drilling site.
One example of a blow-out protector is illustrated in U.S. Pat. No. 2,231,221. In that protector, the packing element is carried on an elongated actuator sleeve provided with a plurality of annular gear teeth. In the event of a blow-out the packing element is driven by the sleeve into abutment with a shoulder located internally in the well hole whereupon the packing element is compressed and the packing buldges from the element into sealing arrangement between the drill pipe and the blow-out protector housing. There are numerous other examples of blow-out protectors in the art which differ in the design of the packing element and the means whereby the element if forced into sealing engagement with the drill pipe. For example see U.S. Pat. Nos. 3,804,174; 2,375,432; 2,139,526; and 1,963,683.
Should the blow-out protector fail, as sometimes happens, catastrophic results ensue. The proposed solution set forth in U.S. Pat. No. 3,804,175 is to increase the pressure in the blow-out protector annulus which in turn forces the elastomeric body of the blow-out protector against the outer wall of the drill string. It would appear however that if a channel were to form between the drill string wall and the elastomeric body that the body could be forced away from the drill string. In addition, increased pressure in the well can put increased stress on the sealing elements of the well and cause a blow-out. Another proposed solution to the blow-out protector failure problem is to mix the oil and the flamable and toxic gases shooting out of the well with liquids which absorb the toxic gases and prevent combustion, see U.S. Pat. No. 4,316,506. This blow-out condition of the well is preferably avoided, as it is very difficult to reseal a well in a blow-out state.
Another factor contributing to a blow-out state is the inability of most blow-out protectors to function when the well pipe has been pulled from the well, as the blow-out protectors work by forcing a rubber body in sealing relationship between the well pipe and casing.